The present invention relates to a printer for printing a color image and, more particularly, to an ink jet system printer of the ink-on-demand type for printing a color image.
Generally, in a color printer, various colors are formed by mixing three primary colors, yellow, magenta and cyan. A color ink jet system printer has been proposed, wherein the above-mentioned three color ink droplets and a black ink droplet are mixed on a record receiving paper.
An example of the color ink jet system printer of the ink-on-demand type is disclosed in copending application, COLOR INK JET SYSTEM PRINTER, Ser. No. 488,827, filed on Apr. 26, 1983 by Yoshio Kanayama and assigned to the same assignee as the present application, wherein a yellow orifice, magenta orifice, cyan orifice and black orifice are provided on a printer head for printing a multi-color image.
However, the conventional color ink jet system printer of the ink-on-demand type does not ensure a clean printing in the gradation printing operation. Generally, a thinned out printing is conducted to achieve the gradation printing. The thinned out printing in the conventional color ink jet system printer of the ink-on-demand type increases the color contrast between the printing position and the non-printing, thinned out position. Thus, a light color printing is not produced in the conventional color ink jet system printer of the ink-on-demand type.
Accordingly, an object of the present invention is to provide a color ink jet system printer of the ink-on-demand type, which ensures a clean printing even in the thinned out printing mode.
Another object of the present invention is to provide a color ink jet system printer of the ink-on-demand type, which produces a light color image.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a white orifice is formed in the printer head in addition to the yellow orifice, magenta orifice, cyan orifice and the black orifice. When the thinned out printing operation is conducted, a white ink droplet is emitted from the white orifice for overlapping the white ink droplet on the yellow, magenta, cyan and/or black ink dropltes. The white ink droplet is mixed with the yellow, magenta, cyan and/or black ink droplets to provide the bleeding, thereby producing a light color printing. Transparent ink can be used instead of the white ink.